Three-dimensional Gross-Pitaevskii solitary waves in optical lattices: stabilization using the artificial quartic kinetic energy induced by lattice shaking

In this Letter, we show that a three-dimensional Bose-Einstein solitary wave can become stable if the dispersion law is changed from quadratic to quartic. We suggest a way to realize the quartic dispersion, using shaken optical lattices. Estimates show that the resulting solitary waves can occupy as little as $\sim 1/20$-th of the Brillouin zone in each of the three directions and contain as many as $N = 10^{3}$ atoms, thus representing a \textit{fully mobile} macroscopic three-dimensional object.Comment: 8 pages, 1 figure, accepted in Phys. Lett.

KNOWING, CHARACTERIZING AND ASSESSING SYSTEMS OF ORGANIC CROP ROTATIONS

The choice of crop rotations in organic stockless cropping systems is the first leverage used to manage technical issues (to maintain soil fertility, to control pest and weeds) and economic issues (to insure income). The RotAB project (French Casdar funding 2008-2010) implemented complementary approaches to better knowing, characterizing and assessing arable crop rotations. Their conception depends on numerous factors such as the types of soil and climate (on which depend the types of crops, yield potential, possibility of mechanical weed control…) or the economic context (existence of outlets and continuity of markets). If nitrogen supply and weed control are the most important agronomic issues of organic farmers in stockless cropping systems, phosphorus availability appears to be the next important issue for soil fertility and system sustainability

Conservation tillage in organic farming

Organic farmers are interested in adopting conservation tillage to preserve soil quality and fertility and to prevent soil erosion. Within the framework of a French national study, we compared conventional (ploughing) and conservation tillage systems in organic farming for arable and vegetable cropping systems. Field experiments and on-farm surveys were conducted in several regions of France in order to assess the effects of different tillage systems on soil fertility (physical, chemical, biological) and on weed and crop development. Conservation tillage techniques induced a more compact soil, an increase of carbon and microorganisms in the first soil layer, and an increase of earthworm biomass for very superficial tillage. Weed control was only a major problem for the very superficial tillage, which in turn generated lower crop yields than conventional tillage. The main issues raised by this programme deal with the long-term effects of these techniques on soil fertility, and the improvement of conservation tillage techniques in organic farming

Wheat yield and quality as influenced by reduced tillage in organic farming

Organic farmers are interested in soil conservation by reduced tillage, techniques well known in conventional agriculture to protect soil quality and limit labor time and energy costs. However, organic farming and reduced tillage can modify weeds, soil structure, and thus soil nitrogen (N) mineralization which strongly influences wheat yield and quality. The main objectives of this study were to analyze how reduced tillage applied to organic wheat influenced (1) grain yield, protein concentration, and weed infestation; (2) deoxynivalenol (DON) contamination on grain; (3) technological quality parameters such as dry gluten, zeleny index, falling number, and gluten index; (4) protein composition (F1, F2, F3, F4, and F5 fractions, and UPP, gliadin/glutenin ratio); and (5) baking test. For this purpose, we analyzed five site-years of data from winter wheat crops where mouldboard ploughing and reduced tillage were compared in three experimental trials (two in France and one in Switzerland). Main results concern wheat yields: the effect of reduced tillage on wheat yield was influenced by several factors such as weed competition. No significant increase in mycotoxin content (DON) due to reduced tillage was detected. Contamination with DON was always below the European threshold for human consumption. The technological quality parameters were less affected by the tillage treatments than grain yield: protein content, gluten index, zeleny index, and falling number showed on average no significant difference between treatments although the protein composition was slightly different. The main results of this study are that the effect of reduced tillage on grain yield depends very much on soil type, weather conditions, and time after conversion, whereas there is only minor impact on wheat quality. This is in contrast to the hypothesis that reduced tillage under organic farming will cause problems in baking quality

Shell potentials for microgravity Bose-Einstein condensates

Extending the understanding of Bose-Einstein condensate (BEC) physics to new geometries and topologies has a long and varied history in ultracold atomic physics. One such new geometry is that of a bubble, where a condensate would be confined to the surface of an ellipsoidal shell. Study of this geometry would give insight into new collective modes, self-interference effects, topology-dependent vortex behavior, dimensionality crossovers from thick to thin shells, and the properties of condensates pushed into the ultradilute limit. Here we discuss a proposal to implement a realistic experimental framework for generating shell-geometry BEC using radiofrequency dressing of magnetically-trapped samples. Such a tantalizing state of matter is inaccessible terrestrially due to the distorting effect of gravity on experimentally-feasible shell potentials. The debut of an orbital BEC machine (NASA Cold Atom Laboratory, aboard the International Space Station) has enabled the operation of quantum-gas experiments in a regime of perpetual freefall, and thus has permitted the planning of microgravity shell-geometry BEC experiments. We discuss specific experimental configurations, applicable inhomogeneities and other experimental challenges, and outline potential experiments.Comment: 6 pages, 3 figure

Observation of ultracold atomic bubbles in orbital microgravity

Substantial leaps in the understanding of quantum systems have been driven by exploring geometry, topology, dimensionality and interactions in ultracold atomic ensembles1–6. A system where atoms evolve while confined on an ellipsoidal surface represents a heretofore unexplored geometry and topology. Realizing an ultracold bubble—potentially Bose–Einstein condensed—relates to areas of interest including quantized-vortex flow constrained to a closed surface topology, collective modes and self-interference via bubble expansion7–17. Large ultracold bubbles, created by inflating smaller condensates, directly tie into Hubble-analogue expansion physics18–20. Here we report observations from the NASA Cold Atom Lab21 facility onboard the International Space Station of bubbles of ultracold atoms created using a radiofrequency-dressing protocol. We observe bubble configurations of varying size and initial temperature, and explore bubble thermodynamics, demonstrating substantial cooling associated with inflation. We achieve partial coverings of bubble traps greater than one millimetre in size with ultracold films of inferred few-micrometre thickness, and we observe the dynamics of shell structures projected into free-evolving harmonic confinement. The observations are among the first measurements made with ultracold atoms in space, using perpetual freefall to explore quantum systems that are prohibitively difficult to create on Earth. This work heralds future studies (in orbital microgravity) of the Bose–Einstein condensed bubble, the character of its excitations and the role of topology in its evolution

Endothelio-Mesenchymal Interaction Controls runx1 Expression and Modulates the notch Pathway to Initiate Aortic Hematopoiesis

SummaryHematopoietic stem cells (HSCs) are produced by a small cohort of hemogenic endothelial cells (ECs) during development through the formation of intra-aortic hematopoietic cell (HC) clusters. The Runx1 transcription factor plays a key role in the EC-to-HC and -HSC transition. We show that Runx1 expression in hemogenic ECs and the subsequent initiation of HC formation are tightly controlled by the subaortic mesenchyme, although the mesenchyme is not a source of HCs. Runx1 and Notch signaling are involved in this process, with Notch signaling decreasing with time in HCs. Inhibiting Notch signaling readily increases HC production in mouse and chicken embryos. In the mouse, however, this increase is transient. Collectively, we show complementary roles of hemogenic ECs and mesenchymal compartments in triggering aortic hematopoiesis. The subaortic mesenchyme induces Runx1 expression in hemogenic-primed ECs and collaborates with Notch dynamics to control aortic hematopoiesis

Perspective on Quantum Bubbles in Microgravity

Progress in understanding quantum systems has been driven by the exploration of the geometry, topology, and dimensionality of ultracold atomic systems. The NASA Cold Atom Laboratory (CAL) aboard the International Space Station has enabled the study of ultracold atomic bubbles, a terrestrially-inaccessible topology. Proof-of-principle bubble experiments have been performed on CAL with an rf-dressing technique; an alternate technique (dual-species interaction-driven bubbles) has also been proposed. Both techniques can drive discovery in the next decade of fundamental physics research in microgravity.Comment: 17 pages, 2 figure

Is diagnosis enough to guide interventions in mental health? Using case formulation in clinical practice

While diagnosis has traditionally been viewed as an essential concept in medicine, particularly when selecting treatments, we suggest that the use of diagnosis alone may be limited, particularly within mental health. The concept of clinical case formulation advocates for collaboratively working with patients to identify idiosyncratic aspects of their presentation and select interventions on this basis. Identifying individualized contributing factors, and how these could influence the person\u27s presentation, in addition to attending to personal strengths, may allow the clinician a deeper understanding of a patient, result in a more personalized treatment approach, and potentially provide a better clinical outcome.<br /

Exploring the limits of ultracold atoms in space

Existing space-based cold atom experiments have demonstrated the utility of microgravity for improvements in observation times and for minimizing the expansion energy and rate of a freely evolving coherent matter wave. In this paper we explore the potential for space-based experiments to extend the limits of ultracold atoms utilizing not just microgravity, but also other aspects of the space environment such as exceptionally good vacuums and extremely cold temperatures. The tantalizing possibility that such experiments may one day be able to probe physics of quantum objects with masses approaching the Planck mass is discussed